Which order to apply room correction tools?

[Buster Chestnut]

I’m not the one asking people to barricade their windows and sand their chimneys. You’re asking people to alter their living spaces and saying that this is something they should do before they intelligently design filters based on their speakers.

You’re the villain here.

Yep, chimney sanding.

 

[thewas]

Room acoustics (room design, optimal placement and treatment) is of course the most important contribution to sound quality but the problem is that especially at lower frequencies where the biggest problems occur treatment is either very bulky (passive absorbers) or expensive (electronic absorption like double bass array) and usually also combined with a low family acceptance factor so EQ/DSP come especially handy.
I personally use DRC since more than 10 years but if I had the free choice I would prefer some medium good loudspeakers in an acoustically optimal environment than the opposite.

 

[Sukram]

I used the Dirac (full version) room correction first. It sucked the power out of my power amplifier. I changed to dbx venu360. It was a total game-changer (together with active crossover). I'm very happy with it.

 

[andrew]

The miniDSP SHD should not be used with MSO. MSO depends on the usage of mono bass -- that is, traditional bass management. But a proper implementation of traditional bass management has the "room correction" after the point at which the multiple channels are summed to form a single mono bass channel, that is, after bass management. From the diagram below, it can be seen that the SHD's Dirac processing is before the mixer. This means that the summed mono signal used for the bass depends, among other things, on the relative phase of the transfer functions of the Left and Right channel Dirac correction in the bass region, which is uncontrolled.
View attachment 117877

The SHD design is just fine for stereo bass, as in a pair of actively biamped two-way speakers. But MSO is not intended for stereo bass. In fact, the whole theory of optimization of multiple subs as originally written by Welti and Devantier assumes mono bass and traditional bass management. There are advocates of stereo bass out there, namely Griesinger, and I don't want to open that can of worms. Rather, I just wanted to warn users about incompatibility with MSO.

Of course, miniDSP will never admit this.

Thanks, Andy, for the great MSO! I’m focused on stereo with main speakers high passed and fleet of mono low passed subs. Your point that applying Dirac on the inputs not making sense is well taken. Any idea of hardware that allows for overall EQ to be applied later in the chain after bass management?

 

[andyc56]

Any idea of hardware that allows for overall EQ to be applied later in the chain after bass management?

The miniDSP DDRC-88A/BM looks like it does Dirac after bass management, but I don't think it's made anymore. Others more familiar with all the latest developments may be able to give a better answer.

I don't have anything against Dirac, it's just that performing it before bass management can mess with the integrity of the mono summed bass signal.

 

[andrew]

The miniDSP DDRC-88A/BM looks like it does Dirac after bass management, but I don't think it's made anymore. Others more familiar with all the latest developments may be able to give a better answer.

I don't have anything against Dirac, it's just that performing it before bass management can mess with the integrity of the mono summed bass signal.

Much appreciated. I’m planning on using mini-DSP SHD Studio to do bass managed before feeding main stereo DAC for front left / right and an old mini-DSP 10x10HD to manage a fleet of mono subs optimised via MSO. It’s not Dirac but I think that I can do overall EQ via PEQ on the mini-DSP as this occurs after bass management.

 

[Keith_W]

Hi @andyc56 I have been trying to get in touch with you. Would you be able to send me a PM? I can't PM you, it seems you have it disabled.

 

[312elements]

The miniDSP DDRC-88A/BM looks like it does Dirac after bass management, but I don't think it's made anymore. Others more familiar with all the latest developments may be able to give a better answer.

I don't have anything against Dirac, it's just that performing it before bass management can mess with the integrity of the mono summed bass signal.

I had that device and it was pretty awful from an adc standpoint. It actually turned me off of ADC in the signal chain, but it seems like modern hardware has more or less made that a non-issue.

 

[andyc56]

Much appreciated. I’m planning on using mini-DSP SHD Studio to do bass managed before feeding main stereo DAC for front left / right and an old mini-DSP 10x10HD to manage a fleet of mono subs optimised via MSO. It’s not Dirac but I think that I can do overall EQ via PEQ on the mini-DSP as this occurs after bass management.

Be careful of the 10x10. It uses fixed-point DSP and is susceptible to significant low-frequency filter response errors when the filters themselves target the lowest frequencies (like HPFs that cut off at around 10 Hz or PEQs centered around 10 Hz). See the images in this review for measured data. The problem is reduced, but not eliminated by running it at a 48 kHz sample rate rather than 96 kHz.

 

[312elements]

I think this subject in general is documented very poorly and I’m surprised that there aren’t better tutorials from better teachers. Most of the tutorials and even threads associated with topic aren’t helpful.

First off the subject of room correction, and crossover design/ bass management really need to be separated even if one impacts the other. It continuously derails conversations.

The second problem is the people who seem to understand the subjects best are bad teachers more interested in hearing themselves talk and flexing their knowledge than they are concerned with helping people.

Most of us can drive a car and we were taught how to operate a motor vehicle without having to understand much about the way a combustion engine works. The execution of performing the measurements, creating the filters, and implementing them can and should be made much more clear by some of these commercial manufacturers. If the assumption of the manufacturers is that the people using their tools, need a degree in XYZ to operate them, then they’re severely limiting their audience.

Dirac and Audyssey are what they are. I’ll call them middle of the road, but they’re relatively easy to use and well documented. The jump from Dirac to something better is a distance too far for many of us and I don’t think it needs to be that way. We have all of the tools we need. What we need now is a clear and repeatable process for success.